What did you worm them with? These are young birds, correct? This seems a little too rapid of an onset for canker, coccidiosis, or worms. Sounds more like young bird sickness (adenovirus). There's not too much you can do for it as it is a virus, but treating for the onset of the possible canker and ecoli infections is usually advisable (stress is what usually turns these things on). Having said that, I can't see the bird or it's behavior from here, so I am just giving a possibility. Also, just because all birds are housed together, doesn't mean they will all get young bird sickness if one becomes sick. Some can die in a couple days, and some can also recover well in a couple weeks or so... you never really know how it will go. I suppose paratyphoid or ecoli could be possibilities also... what color are the droppings? With adenovirus I believe they are typically kind of yellowish as it's hard on the liver, and paratyphoid and ecoli are greenish and smelly.
